The present invention relates to a novel composition, in particular a cosmetic composition, comprising specific amides and pulverulent materials. The invention also relates to the use of certain amides as dispersants for pulverulent materials, as well as to a process for dispersing pulverulent materials.
It is known practice to use pulverulent materials such as pigments or fillers in cosmetic compositions for the purpose in particular of giving these compositions a desired colour. Certain metal oxide pigments, such as titanium dioxide, are also used for their known appreciable anti-UV properties. However, the incorporation of these pulverulent materials into cosmetic compositions is not always easy to carry out. The reason for this is that the appearance of aggregates is frequently observed and the pigments often tend to sediment out over time; the dispersion of the pigments in the composition is then no longer homogeneous. The sedimentation of the pigments no longer makes it possible to conserve the uniformity of the colour of the composition, in particular when it is applied to the skin. This sedimentation can also give rise to a substantial reduction in the efficacy of the antisun protection imparted by pigments with anti-UV properties.
To prevent the aggregation and/or sedimentation of pigments, it has been proposed to use dispersing agents, and in particular branched alkyl esters. For example, patents U.S. Pat. Nos. 5,476,637 and 5,516,506 describe the use of neopentyl glycol esters to help disperse pigments. According to patent application WO 94/18940, it is also known practice to improve the dispersion of titanium oxide pigments by using branched organic compounds such as esters, ethers, hydrocarbons or silicones, and in particular octyldodecyl neopentanoate.
Although these dispersants described in the prior art make it possible to disperse the pigments commonly used in cosmetics, the stability over time of these dispersions is, however, unsatisfactory. The reason for this is that, after storage for several hours, or even several days, it is found that the pigment dispersion does not retain its homogeneity since the pigments sediment out over time.
Moreover, it is known practice from patent U.S. Pat. No. 5,162,315 and patent application JP-A-62-215,537, to use amides comprising at least two alkyl chains to improve the penetration of pharmaceutical active agents into the skin. In patent application WO 88/04167, amides comprising two alkyl chains are used in an antisun or moisturizing composition, in the form of an emulsion, to impart moisture resistance to the composition.
An object of the present invention is to allow the preparation and production of a composition which comprises homogeneously dispersed pulverulent materials and which is stable over time.
The Applicant has discovered, surprisingly and unexpectedly, that by using certain branched amides, an entirely stable dispersion of pulverulent materials can be obtained. Furthermore, the stability of the dispersion thus obtained can be preserved for more than one week, or even more than one month.
Thus, the invention relates to a composition comprising at least one pulverulent material and at least one amide of formula (I) below:
R1xe2x80x94COxe2x80x94NHxe2x80x94R2xe2x80x83xe2x80x83(I)
in which R1 and R2, independently of each other, denote a saturated or unsaturated, branched alkyl radical comprising from 3 to 30 carbon atoms. Preferably, R1 and R2, independently of each other, denote a saturated branched alkyl radical containing from 3 to 20 carbon atoms. More preferably, R1 comprises from 3 to 10 carbon atoms and R2 comprises from 10 to 20 carbon atoms.
Advantageously, R2 denotes a branched radical of formula (II): 
in which R3 and R4, independently of each other, denote a linear alkyl radical containing from 1 to 27 carbon atoms, with the proviso that the total number of carbon atoms in the radical of formula (II) is less than or equal to 30. Preferably, R3 and R4, independently of each other, contain from 2 to 12 carbon atoms, and more preferably from 2 to 10 carbon atoms.
Groups R1 which may be mentioned, for example, are tert-butyl and 2,4,4-trimethylpentyl groups.
Groups R2 which may be mentioned are, in particular, 2-octyldodecyl and 2-butyloctyl groups.
Among the preferred compounds corresponding to the general formula (I), mention may be made in particular of:
N-neopentanoyl-2-octyldodecylamine,
N-neopentanoyl-2-butyloctylamine,
N-(3,5,5-trimethylhexanoyl)-2-octyldodecylamine,
N-(3,5,5-trimethylhexanoyl)-2-butyloctylamine.
The compounds of formula (I) are preferably present in a content ranging from 0.1% to 50% by weight relative to the total weight of the composition, and better still from 2 to 20%.
The pulverulent materials present in the composition can be chosen from pigments, nacres and/or fillers. They are preferably present in a proportion of from 0.1 to 80% by weight relative to the total weight of the composition.
Among the pigments which may be mentioned are inorganic pigments such as titanium oxide, zinc oxide, iron oxide, zirconium oxide and cerium oxide, or mixtures thereof. Nanopigments of these metal oxides which are known for their anti-VU properties can also be used. These nanopigments are used in a known manner in antisun compositions. The term xe2x80x9cnanopigmentsxe2x80x9d means pigments whose average primary particle size does not exceed 100 nm, this size preferably being between 5 nm and 100 nm and even more preferably between 10 and 50 nm. Such coated or uncoated metal oxide nanopigments are products known to those skilled in the art and are described in particular in patent application EP-A-0,518,773, the teaching of which is, in this respect, included in the present description by way of reference.
Inorganic Pigments which may also be mentioned are chromium oxide, manganese violet, ultramarine blue, chromium hydrate and ferric blue. The organic pigments can be chosen from carbon black, pigments of D and C type, and lakes based on cochineal carmine.
The nacres can be chosen from white nacreous pigments such as mica coated with titanium oxide or with bismuth oxychloride, coloured nacreous pigments such as titanium mica coated with iron oxides, titanium mica with, in particular, ferric blue or chromium oxide, titanium mica with an organic pigment of the abovementioned type, as well as nacreous pigments based on bismuth oxychloride.
The fillers can be inorganic or organic, and lamellar or spherical. Mention may be made of talc, mica, silica, kaolin, Nylon powder, poly-xcex2-alanine powder and polyethylene powder, Teflon, lauroyllysine, starch, titanium mica, natural mother-of-pearl, boron nitride, tetrafluoroethylene polymer powders, hollow microspheres such as Expancel (Nobel Industrie), Polytrap (Dow Corning) and silicone resin microbeads (Tospearls from Toshiba, for example), zinc oxide, titanium oxide, precipitated calcium carbonate, magnesium carbonate and hydrocarbonate, hydroxyapatite, hollow silica microspheres (Silica Beads from Maprecos), glass or ceramic microcapsules; metal soaps derived from organic carboxylic acids containing from 8 to 22 carbon atoms, preferably from 12 to 18 carbon atoms, for example zinc, magnesium or lithium stearate, zinc laurate or magnesium myristate.
A subject of the invention is also the amides of formula (Ixe2x80x2) below: 
in which
R1 denotes a saturated or unsaturated, branched alkyl radical containing from 3 to 30 carbon atoms,
R3 and R4, independently of each other, denote a linear alkyl radical containing from 1 to 27 carbon atoms, with the proviso that the total number of carbon atoms in the radical xe2x80x94CH2xe2x80x94CH(R3) (R4) of formula (Ixe2x80x2) is less than or equal to 30.
Preferably, R1, R3 and R4 have the preferred meanings mentioned above for the compounds of formula (I).
These compounds are generally in the form of an oily liquid. It has thus been observed that the dispersion of pulverulent materials in the amides according to the invention is better, more homogeneous and more stable over time than the dispersion of these same pulverulent materials in the oils of the prior art.
The mixture of pulverulent materials and of branched amides which is prepared beforehand can be introduced, for example, into a support which is, acceptable for the intended use, in particular into a cosmetically acceptable support.
The said branched amides and the pulverulent materials can also be introduced separately, either into a pre-prepared composition, in particular a cosmetic composition, or directly during the mixing of all of the constituents of the composition, in particular a cosmetic composition, according to processes that are well known to those skilled in the art.
The composition according to the invention can also comprise at least one oil, chosen in particular from plant, animal, mineral or synthetic oils. Needless to say, a person skilled in the art will take care to use oils which are not harmful to correct dispersing of the pulverulent materials in the composition, in acceptable amounts so as not to adversely affect the said dispersion.
According to a specific embodiment of the composition of the invention, the composition comprises as sole oil a compound of formula (I) as defined above.
The composition can also comprise other fatty substances, such as waxes, which can be chosen from the animal, fossil, plant, mineral or synthetic waxes known per se.
Advantageously, the composition according to the invention can comprise a cosmetically acceptable support.
The composition of the invention can also contain at least one additive chosen from thickeners, surfactants, fragrances, preserving agents, sunscreens, proteins, vitamins, polymers and any other additive conventionally used in cosmetics. The precise amount of each additive is readily determined by a person skilled in the art on the basis of its nature and its function.
Needless to say, a person skilled in the art will take care to select this or these optional additives and/or the amounts thereof such that the advantageous properties, and in particular that of dispersing of the pulverulent materials, intrinsically associated with the compounds of formula (I) in accordance with the invention are not, or are not substantially, adversely affected by the addition or additions envisaged.
The processes for manufacturing the compositions of the invention do not differ in any way from the processes conventionally used, in particular in cosmetics, and which are entirely known to those skilled in the art.
The composition according to the invention can be in the form of a dispersion, an emulsion, in particular a water-in-oil or oil-in-water emulsion, or alternatively in the form of a soft paste.
The cosmetic compositions according to the invention can be in the form of a make-up composition, a skincare composition, a hair composition or an antisun composition.
The make-up compositions can be in the form of an eyeshadow, a face powder, an eyeliner, a foundation, a blusher, a mascara, a lipstick, a lipcare stick, a concealer composition or a tinted cream.
The hair compositions can be in the form of a shampoo, a lotion, a gel, an emulsion, a nonionic vesicular dispersion or a lacquer for the hair and can constitute, for example, a rinse-out composition, to be applied before or after shampooing, before or after dyeing or bleaching, or before, during or after permanent-waving or straightening the hair, a styling or treating lotion or gel, a blow-drying or hair-setting lotion or gel, or a composition for permanent-waving, straightening, dyeing or bleaching the hair.
The invention also relates to the use of an amide of formula (I) as defined above as an agent for dispersing pulverulent materials. The expression xe2x80x9cdispersing agentxe2x80x9d means a compound capable of helping to disperse the said pulverulent materials.
A subject of the invention is also a process for dispersing pulverulent materials, characterized in that the said pulverulent materials are dispersed in a composition comprising at least one amide of formula (I) as defined above.